Dynamo-electric machine and fan motor for vehicle

ABSTRACT

An electric rotating machine and a fan motor for vehicle are obtained, wherein variation width of current waveform resulting from occurrence of coils in a short circuit state is narrowed to reduce vibration and noise. A commutator  26  of the fan motor for vehicle comprises twelve segments  24 , and a pair of positive/negative brushes are press-contacted to the commutator  26 . Among the segments  24 , at least one of pairs of segments that the brushes simultaneously contact have mutually different pitches. Therefore, timing when the coil in the short circuit state occurs at an armature and timing when the coil is released from the short circuit state of one brush deviate from those of the other brush temporally. Accordingly, the variation width of current waveform of electric current supplied to the coil connected to the pair of segments  24  narrows at least. As a result, the vibration of the electric rotating machine, variation of rotating torque, and the noise are considerably reduced, and life thereof is thus extended as well.

TECHNICAL FIELD

The present invention relates to an electric rotating machine and a fanmotor for vehicle, and especially to an electric rotating machine and afan motor for vehicle, in which a positive brush and a negative brushare press-contacted to a commutator comprising a plurality of segmentsso as to supply electricity and commutate.

BACKGROUND ART

Among fan motors for vehicle, a fan motor for vehicle using a permanentmagnet as a field (DC motor) is known. In this type of fan motor forvehicle, generally even number of field magnets are fixed inside a motoryoke so that the field magnets are opposed to each other, and anarmature provided with windings is disposed more internally than thefield magnets.

In this case, for example, even if four field magnets are used to formfour electrodes, because two brushes for commutation (a positive brushand a negative brush) can be incorporated, or for other reasons, thearmature comprises slots in which wave windings are respectivelyprovided between teeth. The windings of the armature are respectivelyelectrically connected to odd number of segments of a commutator,wherein the number of segments is determined in correspondence to thenumber of slots of the armature. The positive brush and the negativebrush are press-contacted to the segments of the commutator.Accordingly, electricity is supplied to the respective slots of thearmature (commutation is carried out) via the brushes and the segments.

In such a DC motor, since the brushes are press-contacted to therespective segments of the commutator, which segments are provided incorrespondence to the respective slots of the armature, so as to supplyelectricity (commutate), as the armature rotates, coils in a shortcircuit state occur, wherein the coils are concurrently made to have thesame potential and the occurrence positions are primarily determined(for example, the occurrence positions are four positions in the casewhere four electrodes and two brushes are used).

The short circuit state of the coils is a state of windings (coils) 40wound on a laminated core of the armature, as shown in FIG. 4. Forexample, when each of a positive brush 42 and a negative brush 44contacts across two mutually adjacent segments 46 of the commutator, therespective two segments 46 (segments of Nos. 6 and 7, and segments ofNos. 12 and 1) have the same potential and current does not flowtherethrough, thus resulting in the short circuit state. In this case,coils A and B connected to the respective two segments 46 of thecommutator are referred to as the coils in the short circuit state. Suchcoils in the short circuit state serially occur, while the occurrencepositions are primarily determined depending upon the positionalrelation between the segments 46 of the commutator, and the positivebrush 42 and the negative brush 44. In FIG. 4, the flow of current isschematically shown by arrows.

In this type of conventional fan motor for vehicle, since the pitches ofthe segments 46 of the commutator are regular, timing when the coil inthe above-described short circuit state occurs, wherein the coil in theshort circuit state serially occurs every time each of the positivebrush 42 and the negative brush 44 contacts across two segments 46 ofthe commutator, and timing when the coil is released from the shortcircuit state (timing of switching from the short circuit state to aconductive state) of one brush are coincident with those of the otherbrush. This has been a cause that a value of electric current suppliedto the respective slots of the armature changes rapidly in a short timeand falls into ununiform disorder (variation width of current waveformchanges considerably in waves).

In this manner, the timing when the coil in the above-described shortcircuit state occurs, wherein the coil in the short circuit stateserially occurs every time each of the positive brush 42 and thenegative brush 44 contacts across two segments of the commutator, andthe timing when the coil is released from the short circuit state of onebrush are coincident with those of the other brush, and thus, thevariation width of current waveform widens. This results in vibration ofthe motor, variation of rotating torque, and generation of noise. Therehas been eagerness for countermeasures therefor.

In view of the above facts, it is an object of the present invention toobtain an electric rotating machine and a fan motor for vehicle, whereinvariation width of current waveform resulting from occurrence of coilsin a short circuit state is narrowed to reduce the vibration and thenoise.

DISCLOSURE OF THE INVENTION

In order to attain the above object, a first aspect of the presentinvention is an electric rotating machine comprising: a motor yoke; afield magnet fixed inside the motor yoke; an armature comprising arotating shaft at a central portion of a laminated core on whichwindings are wound, wherein a commutator comprising a plurality ofsegments, in which at least one pair of segments comprise mutuallydifferent peripheral widths, is attached to an end portion of therotating shaft; and a plurality of brushes disposed opposite each otherwith the commutator therebetween, so as to slide on the commutator ofthe armature.

A second aspect of the present invention, according to the first aspect,is the electric rotating machine, wherein the plurality of segmentsoften include variable width segments, and the variable width segmentseach often comprise a peripheral width varied within a range from 1.5%to 40% with respect to a reference width defined by a first formula of(360°/number of segments).

A third aspect of the present invention, according to the second aspect,is the electric rotating machine, wherein the plurality of segmentsoften include some types of variable width segments whose peripheralwidth varies from the reference width, wherein the number of typesthereof is not larger than the number defined by a second formula of(number of segments/2)+1.

A fourth aspect of the present invention, according to the third aspect,is the electric rotating machine, wherein the plurality of segmentsoften include reference width segments, and the reference width segmentseach often comprise a peripheral width substantially equal to thereference width.

A fifth aspect of the present invention, according to the fourth aspect,is the electric rotating machine, wherein at least one of the variablewidth segments often comprises a peripheral width widened at apredetermined rate with respect to the reference width, and at leastanother variable width segment often comprises a peripheral widthnarrowed at a rate substantially equal to the predetermined rate withrespect to the reference width.

A sixth aspect of the present invention, according to the fifth aspect,is the electric rotating machine, wherein a peripheral width of one ofthe variable width segments is often different from a peripheral widthof another variable width segment provided opposite said one of thevariable width segments with respect to a center of the commutator, andperipheral widths of segments other than said one and said anothervariable width segments are often respectively substantially equal toperipheral widths of the segments respectively provided opposite saidsegments other than said one and said another variable width segmentswith respect to the center of the commutator.

A seventh aspect of the present invention, according to the sixthaspect, is the electric rotating machine often further comprising aplurality of pawls, which are respectively formed to the plurality ofsegments and with which portions of the windings are respectivelyengaged in a conductive state, wherein at least one of the plurality ofpawls is provided at a position displaced from the peripheral center ofthe respective segment.

An eighth aspect of the present invention, according to the secondaspect, is the electric rotating machine, wherein the plurality ofsegments often include reference width segments, and the reference widthsegments each often comprise a peripheral width substantially equal tothe reference width.

A ninth aspect of the present invention, according to the eighth aspect,is the electric rotating machine, wherein at least one of the variablewidth segments often comprises a peripheral width widened at apredetermined rate with respect to the reference width, and at leastanother variable width segment often comprises a peripheral widthnarrowed at a rate substantially equal to the predetermined rate withrespect to the reference width.

A tenth aspect of the present invention, according to the second aspect,is the electric rotating machine, wherein at least one of the variablewidth segments often comprises a peripheral width widened at apredetermined rate with respect to the reference width, and at leastanother variable width segment often comprises a peripheral widthnarrowed at a rate substantially equal to the predetermined rate withrespect to the reference width.

An eleventh aspect of the present invention, according to the secondaspect, is the electric rotating machine often further comprising aplurality of pawls, which are respectively formed to the plurality ofsegments and with which portions of the windings are respectivelyengaged in a conductive state, wherein at least one of the plurality ofpawls is provided at a position displaced from the peripheral center ofthe respective segment.

A twelfth aspect of the present invention, according to the firstaspect, is the electric rotating machine, wherein the plurality ofsegments often include some types of variable width segments whoseperipheral width varies from the reference width, wherein the number oftypes thereof is not larger than the number defined by a second formulaof (number of segments/2)+1.

A thirteenth aspect of the present invention, according to the twelfthaspect, is the electric rotating machine, wherein the plurality ofsegments often include reference width segments, and the reference widthsegments each often comprise a peripheral width substantially equal tothe reference width.

A fourteenth aspect of the present invention, according to the twelfthaspect, is the electric rotating machine often further comprising aplurality of pawls, which are respectively formed to the plurality ofsegments and with which portions of the windings are respectivelyengaged in a conductive state, wherein at least one of the plurality ofpawls is provided at a position displaced from the peripheral center ofthe respective segment.

A fifteenth aspect of the present invention, according to the firstaspect, is the electric rotating machine often further comprising aplurality of pawls, which are respectively formed to the plurality ofsegments and with which portions of the windings are respectivelyengaged in a conductive state, wherein at least one of the plurality ofpawls is provided at a position displaced from the peripheral center ofthe respective segment.

A sixteenth aspect of the present invention is a fan motor for vehiclecomprising: a motor yoke; a field magnet fixed inside the motor yoke; anarmature comprising a rotating shaft at a central portion of a laminatedcore on which windings are wound, wherein a commutator comprising aplurality of segments, in which at least one pair of segments comprisemutually different peripheral widths, is attached to an end portion ofthe rotating shaft; a plurality of brushes disposed opposite each otherwith the commutator therebetween, so as to slide on the commutator ofthe armature; and a fan attached to the rotating shaft so as to rotateas the armature rotates.

A seventeenth aspect of the present invention, according to thesixteenth aspect, is the fan motor for vehicle, wherein the plurality ofsegments often include variable width segments, and the variable widthsegments each often comprise a peripheral width varied within a rangefrom 1.5% to 40% with respect to a reference width defined by a firstformula of (360°/number of segments).

An eighteenth aspect of the present invention, according to theseventeenth aspect, is the fan motor for vehicle, wherein the pluralityof segments often include some types of variable width segments whoseperipheral width varies from the reference width, wherein the number oftypes thereof is not larger than the number defined by a second formulaof (number of segments/2)+1; wherein at least one of the variable widthsegments often comprises a peripheral width widened at a predeterminedrate with respect to the reference width, and at least another variablewidth segment often comprises a peripheral width narrowed at a ratesubstantially equal to the predetermined rate with respect to thereference width; and wherein a peripheral width of one of the variablewidth segments is often different from a peripheral width of anothervariable width segment provided opposite said one of the variable widthsegments with respect to a center of the commutator, and peripheralwidths of segments other than said one and said another variable widthsegments are often respectively substantially equal to peripheral widthsof the segments respectively provided opposite said segments other thansaid one and said another variable width segments with respect to thecenter of the commutator.

A nineteenth aspect of the present invention, according to theseventeenth aspect, is the fan motor for vehicle, wherein at least oneof the variable width segments often comprises a peripheral widthwidened at a predetermined rate with respect to the reference width, andat least another variable width segment often comprises a peripheralwidth narrowed at a rate substantially equal to the predetermined ratewith respect to the reference width.

A twentieth aspect of the present invention, according to the sixteenthaspect, is the fan motor for vehicle, wherein the plurality of segmentsoften include some types of variable width segments whose peripheralwidth varies from the reference width, wherein the number of typesthereof is not larger than the number defined by a second formula of(number of segments/2)+1.

In the electric rotating machine according to the first aspect of thepresent invention, rotating force is generated for the armature byinteraction between a magnetic field formed by the armature on which thewindings get conductive via the commutator and a magnetic field formedby the field magnets fixed inside the motor yoke, and the armature isrotated by the rotating force.

In the electric rotating machine, among the plurality of segments of thecommutator, at least one pair of segments comprise mutually differentperipheral widths. Therefore, a period of switching current to therespective segments becomes irregular, and thus, magnetic exciting-forcedoes not concentrate on a certain frequency.

Further, since at least one pair of segments comprise mutually differentperipheral widths as described above, contact timing and contact-releasetiming of one brush deviate from those of the other brush. Accordingly,variation width of current waveform narrows at least in a value ofelectric current supplied to the coil (slot) connected to the pair ofsegments. As a result, vibration of the electric rotating machine,variation of rotating torque, and noise are reduced.

In the electric rotating machine according to the second aspect of thepresent invention, the plurality of segments include variable widthsegments, and the variable width segments each comprise a peripheralwidth varied within a range from 1.5% to 40% with respect to a referencewidth defined by a first formula of (360°/number of segments).

When each of the brushes contacts across two mutually adjacent segmentsof the commutator, the two segments have the same potential and currentdoes not flow therethrough, thus resulting in a short circuit state. Inthis case, the coils connected to the respective two segments result incoils in the short circuit state. As the armature rotates, such coils inthe short circuit state serially occur.

In the electric rotating machine, the plurality of segments include theabove-mentioned variable width segments. Therefore, when at least one ofthe segments across which each of a positive brush and a negative brushcontacts is the variable width segment, the contact timing andcontact-release timing of one brush, i.e., timing when the coil in theabove-described short circuit state occurs and timing when the coil isreleased from the short circuit state (timing of switching from theshort circuit state to a conductive state) thereof, deviate from thoseof the other brush. Accordingly, variation width of current waveformnarrows in a value of electric current supplied to the coil (slot)connected to the variable width segment. As a result, vibration of theelectric rotating machine, variation of rotating torque, and noise arereduced.

In the electric rotating machine according to the third aspect of thepresent invention, the plurality of segments include some types ofvariable width segments whose peripheral width varies from the referencewidth, wherein the number of types thereof is not larger than the numberdefined by a second formula of (number of segments/2)+1.

When each of the brushes contacts across two mutually adjacent segmentsof the commutator, the two segments have the same potential and currentdoes not flow therethrough, thus resulting in a short circuit state. Inthis case, the coils connected to the respective two segments result incoils in the short circuit state. As the armature rotates, such coils inthe short circuit state serially occur.

In the electric rotating machine, the plurality of segments include sometypes of variable width segments whose peripheral width varies from thereference width, wherein the number of types thereof is not larger thanthe number defined by the above second formula. Therefore, when at leastone of the segments across which each of the positive brush and thenegative brush contacts is the variable width segment, the contacttiming and contact-release timing of one brush, i.e., timing when thecoil in the above-described short circuit state occurs and timing whenthe coil is released from the short circuit state (timing of switchingfrom the short circuit state to a conductive state) thereof, deviatefrom those of the other brush. Accordingly, variation width of currentwaveform narrows in a value of electric current supplied to the coil(slot) connected to the variable width segment. As a result, vibrationof the electric rotating machine, variation of rotating torque, andnoise are reduced.

In the electric rotating machine according to the fourth aspect of thepresent invention, the plurality of segments include reference widthsegments, and the reference width segments each comprise a peripheralwidth substantially equal to the reference width defined by a firstformula of (360°/number of segments). Therefore, when each of thepositive brush and the negative brush contacts across the referencewidth segment and the variable width segment, the contact timing andcontact-release timing of one brush, i.e., timing when the coil in theabove-described short circuit state occurs and timing when the coil isreleased from the short circuit state (timing of switching from theshort circuit state to a conductive state) thereof, deviate from thoseof the other brush. Accordingly, variation width of current waveformnarrows in a value of electric current supplied to the coil (slot)connected to the segments. As a result, vibration of the electricrotating machine, variation of rotating torque, and noise are reduced.

In the electric rotating machine according to the fifth aspect of thepresent invention, at least one of the variable width segments comprisesa peripheral width widened at a predetermined rate with respect to thereference width (hereinafter, this variable width segment isappropriately referred to as a “wide width segment”), and at leastanother variable width segment comprises a peripheral width narrowed ata rate substantially equal to the predetermined rate with respect to thereference width (hereinafter, this variable width segment isappropriately referred to as a “narrow width segment”). Accordingly, theperipheral widths of the segments other than the wide width segment andthe narrow width segment can be made the same. As a result, thecommutator is easily designed.

In the electric rotating machine according to the sixth aspect of thepresent invention, a peripheral width of one of the variable widthsegments is different from a peripheral width of another variable widthsegment provided opposite said one of the variable width segments withrespect to a center of the commutator.

Therefore, even if the peripheral widths of the segments other than theone variable width segment and the another variable width segment (i.e.,those of the variable width segments or the reference width segmentswhich are quite different from the one variable width segment and fromthe another variable width segment) are made the same, timing when thepositive brush contacts the respective segments and timing when thepositive brush is released from the contact state certainly deviate fromthose for the negative brush.

For example, when the segments are formed to the commutator, slits areformed by a cutting tool to the commutator to which the segments havenot been formed yet. In order to form the slits, cutting tools areconnected to each other so that they are respectively oriented towardthe center of the commutator in the radial direction, and a plurality ofslits are then formed at a time by the cutting tools. After forming theslits, the cutting tools are separated from the commutator, and then,the plurality of cutting tools are rotated around the center of thecommutator, or the commutator itself is rotated, such that anotherplurality of slits are formed at a time at other positions of thecommutator around the center thereof.

In the electric rotating machine of the present invention, theperipheral widths of the segments other than the one variable widthsegment and the another variable width segment are respectively the sameas those of the segments locating on the opposite sides thereof withrespect to a center of the commutator. Therefore, when the slits areformed at other positions thereof as described above, withoutindividually adjusting the respective rotating angles of the pluralityof cutting tools, all of the cutting tools or the commutator isintegrally rotated around the center of the commutator by apredetermined angle (i.e., an angle corresponding to the peripheralwidths of the segments) so as to form the slits to the commutator. As aresult, the operation efficiency is improved.

In the electric rotating machine according to the seventh aspect of thepresent invention, pawls are respectively formed to the plurality ofsegments, and portions of the windings are respectively engaged with thepawls in a conductive state, such that the segments get conductive tothe windings via the pawls.

In general, the pawls are respectively formed at the peripheral centersof the segments. In the present invention, however, since at least oneof the segments has the peripheral width which varies from those of theother segments, if the pawls are respectively formed simply at theperipheral centers of the segments, the pawls are positioned around theaxis of the commutator at irregular intervals.

In the electric rotating machine, since at least one of the pawls isformed at a position circumferentially displaced from the peripheralcenter of the respective segment, the pawls can be positioned around theaxis of the commutator at regular intervals.

In this manner, if at least one of the pawls is formed at a positioncircumferentially displaced from the peripheral center of the respectivesegment such that the pawls can be positioned around the axis of thecommutator at regular intervals, when portions of the windings arerespectively connected to the pawls, the windings are serially connectedwhile the commutator (armature) is rotated by a predetermined angle. Asa result, the operation efficiency is improved. In the case where thewindings are automatically connected to the pawls by a winding device, arobot or the like, the winding device, the robot or the like is easilycontrolled.

In the electric rotating machine according to the eighth aspect of thepresent invention, the plurality of segments include reference widthsegments, and the reference width segments each comprise a peripheralwidth substantially equal to the reference width defined by a firstformula of (360°/number of segments). Therefore, when each of thepositive brush and the negative brush contacts across the referencewidth segment and the variable width segment, the contact timing andcontact-release timing of one brush, i.e., timing when the coil in theabove-described short circuit state occurs and timing when the coil isreleased from the short circuit state (timing of switching from theshort circuit state to a conductive state) thereof, deviate from thoseof the other brush. Accordingly, variation width of current waveformnarrows in a value of electric current supplied to the coil (slot)connected to the segments. As a result, vibration of the electricrotating machine, variation of rotating torque, and noise are reduced.

In the electric rotating machine according to the ninth aspect of thepresent invention, at least one of the variable width segments comprisesa peripheral width widened at a predetermined rate with respect to thereference width (hereinafter, this variable width segment isappropriately referred to as a “wide width segment”), and at leastanother variable width segment comprises a peripheral width narrowed ata rate substantially equal to the predetermined rate with respect to thereference width (hereinafter, this variable width segment isappropriately referred to as a “narrow width segment”). Accordingly, theperipheral widths of the segments other than the wide width segment andthe narrow width segment can be made the same. As a result, thecommutator is easily designed.

In the electric rotating machine according to the tenth aspect of thepresent invention, at least one of the variable width segments comprisesa peripheral width widened at a predetermined rate with respect to thereference width (hereinafter, this variable width segment isappropriately referred to as a “wide width segment”), and at leastanother variable width segment comprises a peripheral width narrowed ata rate substantially equal to the predetermined rate with respect to thereference width (hereinafter, this variable width segment isappropriately referred to as a “narrow width segment”). Accordingly, theperipheral widths of the segments other than the wide width segment andthe narrow width segment can be made the same. As a result, thecommutator is easily designed.

In the electric rotating machine according to the eleventh aspect of thepresent invention, pawls are respectively formed to the plurality ofsegments, and portions of the windings are respectively engaged with thepawls in a conductive state, such that the segments get conductive tothe windings via the pawls.

In general, the pawls are respectively formed at the peripheral centersof the segments. In the present invention, however, since at least oneof the segments has the peripheral width which varies from those of theother segments, if the pawls are respectively formed simply at theperipheral centers of the segments, the pawls are positioned around theaxis of the commutator at irregular intervals.

In the electric rotating machine, since at least one of the pawls isformed at a position circumferentially displaced from the peripheralcenter of the respective segment, the pawls can be positioned around theaxis of the commutator at regular intervals.

In this manner, if at least one of the pawls is formed at a positioncircumferentially displaced from the peripheral center of the respectivesegment such that the pawls can be positioned around the axis of thecommutator at regular intervals, when portions of the windings arerespectively connected to the pawls, the windings are serially connectedwhile the commutator (armature) is rotated by a predetermined angle. Asa result, the operation efficiency is improved. In the case where thewindings are automatically connected to the pawls by a winding device, arobot or the like, the winding device, the robot or the like is easilycontrolled.

In the electric rotating machine according to the twelfth aspect of thepresent invention, the plurality of segments include some types ofvariable width segments whose peripheral width varies from the referencewidth, wherein the number of types thereof is not larger than the numberdefined by a second formula of (number of segments/2)+1.

When each of the brushes contacts across two mutually adjacent segmentsof the commutator, the two segments have the same potential and currentdoes not flow therethrough, thus resulting in a short circuit state. Inthis case, the coils connected to the respective two segments result incoils in the short circuit state. As the armature rotates, such coils inthe short circuit state serially occur.

In the electric rotating machine, the plurality of segments include sometypes of variable width segments whose peripheral width varies from thereference width, wherein the number of types thereof is not larger thanthe number defined by the above second formula. Therefore, when at leastone of the segments across which each of the positive brush and thenegative brush contacts is the variable width segment, the contacttiming and contact-release timing of one brush, i.e., timing when thecoil in the above-described short circuit state occurs and timing whenthe coil is released from the short circuit state (timing of switchingfrom the short circuit state to a conductive state) thereof, deviatefrom those of the other brush. Accordingly, variation width of currentwaveform narrows in a value of electric current supplied to the coil(slot) connected to the variable width segment. As a result, vibrationof the electric rotating machine, variation of rotating torque, andnoise are reduced.

In the electric rotating machine according to the thirteenth aspect ofthe present invention, the plurality of segments include reference widthsegments, and the reference width segments each comprise a peripheralwidth substantially equal to the reference width defined by a firstformula of (360°/number of segments). Therefore, when each of thepositive brush and the negative brush contacts across the referencewidth segment and the variable width segment, the contact timing andcontact-release timing of one brush, i.e., timing when the coil in theabove-described short circuit state occurs and timing when the coil isreleased from the short circuit state (timing of switching from theshort circuit state to a conductive state) thereof, deviate from thoseof the other brush. Accordingly, variation width of current waveformnarrows in a value of electric current supplied to the coil (slot)connected to the segments. As a result, vibration of the electricrotating machine, variation of rotating torque, and noise are reduced.

In the electric rotating machine according to the fourteenth aspect ofthe present invention, pawls are respectively formed to the plurality ofsegments, and portions of the windings are respectively engaged with thepawls in a conductive state, such that the segments get conductive tothe windings via the pawls.

In general, the pawls are respectively formed at the peripheral centersof the segments. In the present invention, however, since at least oneof the segments has the peripheral width which varies from those of theother segments, if the pawls are respectively formed simply at theperipheral centers of the segments, the pawls are positioned around theaxis of the commutator at irregular intervals.

In the electric rotating machine, since at least one of the pawls isformed at a position circumferentially displaced from the peripheralcenter of the respective segment, the pawls can be positioned around theaxis of the commutator at regular intervals.

In this manner, if at least one of the pawls is formed at a positioncircumferentially displaced from the peripheral center of the respectivesegment such that the pawls can be positioned around the axis of thecommutator at regular intervals, when portions of the windings arerespectively connected to the pawls, the windings are serially connectedwhile the commutator (armature) is rotated by a predetermined angle. Asa result, the operation efficiency is improved. In the case where thewindings are automatically connected to the pawls by a winding device, arobot or the like, the winding device, the robot or the like is easilycontrolled.

In the electric rotating machine according to the fifteenth aspect ofthe present invention, pawls are respectively formed to the plurality ofsegments, and portions of the windings are respectively engaged with thepawls in a conductive state, such that the segments get conductive tothe windings via the pawls.

In general, the pawls are respectively formed at the peripheral centersof the segments. In the present invention, however, since at least oneof the segments has the peripheral width which varies from those of theother segments, if the pawls are respectively formed simply at theperipheral centers of the segments, the pawls are positioned around theaxis of the commutator at irregular intervals.

In the electric rotating machine, since at least one of the pawls isformed at a position circumferentially displaced from the peripheralcenter of the respective segment, the pawls can be positioned around theaxis of the commutator at regular intervals.

In this manner, if at least one of the pawls is formed at a positioncircumferentially displaced from the peripheral center of the respectivesegment such that the pawls can be positioned around the axis of thecommutator at regular intervals, when portions of the windings arerespectively connected to the pawls, the windings are serially connectedwhile the commutator (armature) is rotated by a predetermined angle. Asa result, the operation efficiency is improved. In the case where thewindings are automatically connected to the pawls by a winding device, arobot or the like, the winding device, the robot or the like is easilycontrolled.

In the fan motor for vehicle according to the sixteenth aspect of thepresent invention, rotating force is generated for the armature byinteraction between a magnetic field formed by the armature on which thewindings get conductive via the commutator and a magnetic field formedby the field magnets fixed inside the motor yoke, and the armature isrotated by the rotating force such that the fan rotates.

In the fan motor for vehicle, among the plurality of segments of thecommutator, at least one pair of segments comprise mutually differentperipheral widths. Therefore, a period of switching current to therespective segments becomes irregular, and thus, magnetic exciting-forcedoes not concentrate on a certain frequency.

Further, since at least one pair of segments comprise mutually differentperipheral widths as described above, contact timing and contact-releasetiming of one brush deviate from those of the other brush. Accordingly,variation width of current waveform narrows at least in a value ofelectric current supplied to the coil (slot) connected to the pair ofsegments. As a result, vibration of the fan motor for vehicle, variationof rotating torque, and noise are reduced.

In the fan motor for vehicle according to the seventeenth aspect of thepresent invention, the plurality of segments include variable widthsegments, and the variable width segments each comprise a peripheralwidth varied within a range from 1.5% to 40% with respect to a referencewidth defined by a first formula of (360°/number of segments).

When each of the brushes contacts across two mutually adjacent segmentsof the commutator, the two segments have the same potential and currentdoes not flow therethrough, thus resulting in a short circuit state. Inthis case, the coils connected to the respective two segments result incoils in the short circuit state. As the armature rotates, such coils inthe short circuit state serially occur.

In the fan motor for vehicle, the plurality of segments include theabove-mentioned variable width segments. Therefore, when at least one ofthe segments across which each of a positive brush and a negative brushcontacts is the variable width segment, the contact timing andcontact-release timing of one brush, i.e., timing when the coil in theabove-described short circuit state occurs and timing when the coil isreleased from the short circuit state (timing of switching from theshort circuit state to a conductive state) thereof, deviate from thoseof the other brush. Accordingly, variation width of current waveformnarrows in a value of electric current supplied to the coil (slot)connected to the variable width segment. As a result, vibration of thefan motor for vehicle, variation of rotating torque, and noise arereduced.

In the fan motor for vehicle according to the eighteenth aspect of thepresent invention, the plurality of segments include some types ofvariable width segments whose peripheral width varies from the referencewidth, wherein the number of types thereof is not larger than the numberdefined by a second formula of (number of segments/2)+1. Further, in thefan motor for vehicle, at least one of the variable width segmentscomprises a peripheral width widened at a predetermined rate withrespect to the reference width (hereinafter, this variable width segmentis appropriately referred to as a “wide width segment”), and at leastanother variable width segment comprises a peripheral width narrowed ata rate substantially equal to the predetermined rate with respect to thereference width (hereinafter, this variable width segment isappropriately referred to as a “narrow width segment”).

When each of the brushes contacts across two mutually adjacent segmentsof the commutator, the two segments have the same potential and currentdoes not flow therethrough, thus resulting in a short circuit state. Inthis case, the coils connected to the respective two segments result incoils in the short circuit state. As the armature rotates, such coils inthe short circuit state serially occur.

In the fan motor for vehicle, the plurality of segments include theabove-described plurality of variable width segments. Therefore, when atleast one of the segments across which each of the positive brush andthe negative brush contacts is the variable width segment, the contacttiming and contact-release timing of one brush, i.e., timing when thecoil in the above-described short circuit state occurs and timing whenthe coil is released from the short circuit state (timing of switchingfrom the short circuit state to a conductive state) thereof, deviatefrom those of the other brush. Accordingly, variation width of currentwaveform narrows in a value of electric current supplied to the coil(slot) connected to the variable width segment. As a result, vibrationof the fan motor for vehicle, variation of rotating torque, and noiseare reduced.

A peripheral width of one of the variable width segments is differentfrom a peripheral width of another variable width segment providedopposite said one of the variable width segments with respect to acenter of the commutator.

Therefore, even if the peripheral widths of the segments other than theone variable width segment and the another variable width segment (i.e.,those of the variable width segments or the reference width segmentswhich are quite different from the one variable width segment and fromthe another variable width segment) are made the same, timing when thepositive brush contacts the respective segments and timing when thepositive brush is released from the contact state certainly deviate fromthose for the negative brush.

For example, when the segments are formed to the commutator, slits areformed by a cutting tool to the commutator to which the segments havenot been formed yet. In order to form the slits, cutting tools areconnected to each other so that they are respectively oriented towardthe center of the commutator in the radial direction, and a plurality ofslits are then formed at a time by the cutting tools. After forming theslits, the cutting tools are separated from the commutator, and then,the plurality of cutting tools are rotated around the center of thecommutator, or the commutator itself is rotated, such that anotherplurality of slits are formed at a time at other positions of thecommutator around the center thereof.

In the fan motor for vehicle of the present invention, the peripheralwidths of the segments other than the one variable width segment and theanother variable width segment are respectively the same as those of thesegments locating on the opposite sides thereof with respect to a centerof the commutator. Therefore, when the slits are formed at otherpositions thereof as described above, without individually adjusting therespective rotating angles of the plurality of cutting tools, all of thecutting tools or the commutator is integrally rotated around the centerof the commutator by a predetermined angle (i.e., an angle correspondingto the peripheral widths of the segments) so as to form the slits to thecommutator. As a result, the operation efficiency is improved.

In the fan motor for vehicle according to the nineteenth aspect of thepresent invention, at least one of the variable width segments comprisesa peripheral width widened at a predetermined rate with respect to thereference width (hereinafter, this variable width segment isappropriately referred to as a “wide width segment”), and at leastanother variable width segment comprises a peripheral width narrowed ata rate substantially equal to the predetermined rate with respect to thereference width (hereinafter, this variable width segment isappropriately referred to as a “narrow width segment”). Accordingly, theperipheral widths of the segments other than the wide width segment andthe narrow width segment can be made the same. As a result, thecommutator is easily designed.

In the fan motor for vehicle according to the twentieth aspect of thepresent invention, the plurality of segments include some types ofvariable width segments whose peripheral width varies from the referencewidth, wherein the number of types thereof is not larger than the numberdefined by a second formula of (number of segments/2)+1.

When each of the brushes contacts across two mutually adjacent segmentsof the commutator, the two segments have the same potential and currentdoes not flow therethrough, thus resulting in a short circuit state. Inthis case, the coils connected to the respective two segments result incoils in the short circuit state. As the armature rotates, such coils inthe short circuit state serially occur.

In the fan motor for vehicle, the plurality of segments include sometypes of variable width segments whose peripheral width varies from thereference width, wherein the number of types thereof is not larger thanthe number defined by the above second formula. Therefore, when at leastone of the segments across which each of the positive brush and thenegative brush contacts is the variable width segment, the contacttiming and contact-release timing of one brush, i.e., timing when thecoil in the above-described short circuit state occurs and timing whenthe coil is released from the short circuit state (timing of switchingfrom the short circuit state to a conductive state) thereof, deviatefrom those of the other brush. Accordingly, variation width of currentwaveform narrows in a value of electric current supplied to the coil(slot) connected to the variable width segment. As a result, vibrationof the fan motor for vehicle, variation of rotating torque, and noiseare reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic cross-sectional view showing a structure of acommutator of a fan motor for vehicle (electric rotating machine)according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing an overall structure of the fanmotor for vehicle (electric rotating machine) according to the firstembodiment of the present invention.

FIG. 3 is a schematic developed view showing a structure of thecommutator according to the first embodiment of the present invention.

FIG. 4 is a schematic developed view showing a structure of aconventional commutator.

FIG. 5 is a schematic cross-sectional view showing an example of thecommutator of the fan motor for vehicle (electric rotating machine)according to a second embodiment of the present invention.

FIG. 6 is a schematic cross-sectional view showing another example ofthe commutator of the fan motor for vehicle (electric rotating machine)according to the second embodiment of the present invention.

FIG. 7 is a schematic cross-sectional view showing another example ofthe commutator of the fan motor for vehicle (electric rotating machine)according to the second embodiment of the present invention.

FIG. 8 is a schematic cross-sectional view showing another example ofthe commutator of the fan motor for vehicle (electric rotating machine)according to the second embodiment of the present invention.

FIG. 9 is a schematic cross-sectional view showing another example ofthe commutator of the fan motor for vehicle (electric rotating machine)according to the second embodiment of the present invention.

FIG. 10 is a schematic cross-sectional view showing another example ofthe commutator of the fan motor for vehicle (electric rotating machine)according to the second embodiment of the present invention.

FIG. 11 is a diagram showing measurement data obtained by an experimentof characteristics of changing magnetic exciting-force of the fan motorfor vehicle (electric rotating machine) according to the secondembodiment of the present invention.

FIG. 12 is a diagram showing measurement data obtained by the experimentof the characteristics of changing magnetic exciting-force of the fanmotor for vehicle (electric rotating machine) according to the secondembodiment of the present invention.

FIG. 13 is a schematic cross-sectional view showing an example of thecommutator of the fan motor for vehicle (electric rotating machine)according to a third embodiment of the present invention.

FIG. 14 is a schematic cross-sectional view showing another example ofthe commutator of the fan motor for vehicle (electric rotating machine)according to the third embodiment of the present invention.

FIG. 15 is a schematic cross-sectional view showing another example ofthe commutator of the fan motor for vehicle (electric rotating machine)according to the third embodiment of the present invention.

FIG. 16 is a schematic cross-sectional view showing another example ofthe commutator of the fan motor for vehicle (electric rotating machine)according to the third embodiment of the present invention.

FIG. 17 is a schematic cross-sectional view showing another example ofthe commutator of the fan motor for vehicle (electric rotating machine)according to the third embodiment of the present invention.

FIG. 18 is a schematic cross-sectional view showing another example ofthe commutator of the fan motor for vehicle (electric rotating machine)according to the third embodiment of the present invention.

FIG. 19 is a diagram showing measurement data obtained by an experimentof the characteristics of changing magnetic exciting-force of the fanmotor for vehicle (electric rotating machine) according to the thirdembodiment of the present invention.

FIG. 20 is a schematic cross-sectional view showing an example of thecommutator of the fan motor for vehicle (electric rotating machine)according to a fourth embodiment of the present invention.

FIG. 21 is a cross-sectional view showing an overall structure of thefan motor for vehicle (electric rotating machine) according to thefourth embodiment of the present invention.

MOST PREFERRED EMBODIMENTS FOR IMPLEMENTING THE INVENTION

(First Embodiment)

FIG. 2 is a cross-sectional view showing an overall structure of a fanmotor for vehicle 10, which is an electric rotating machine, accordingto a first embodiment of the present invention.

The fan motor for vehicle 10 is applied to drive, for example, a siroccofan S serving as a fan. A plurality of (e.g., four) field magnets 14 arefixed at predetermined intervals inside a motor yoke 12, and an armature16 is disposed more internally than the field magnets 14.

The armature 16 has a rotating shaft 20 at a central portion of alaminated core 18. Further, windings are respectively provided betweenteeth of the laminated core 18 to form slots 22. In the present firstembodiment, the number of slots 22 (teeth) is twelve.

Coils (windings) 23 of the slots 22 are connected to a commutator 26having twelve segments 24 so that the coils 23 respectively correspondto the segments 24. FIG. 3 is a schematic developed view showing astructure of the commutator 26.

A pair of positive/negative brushes 28 (only one brush is shown in FIG.2) are press-contacted to the commutator 26. The width dimension of thebrush 28 is made substantially the same as that of the segment 24. Thebrushes 28 and the commutator 26 supply electricity to the respectiveslots 22 (coils 23) of the armature 16 (i.e., commutate).

As shown in FIG. 1, among the segments 24 of the commutator 26, whichsegments are adjacent to each other having respective pitches “a” to“l”, at least one of pairs of segments 24 that the pair ofpositive/negative brushes 28 simultaneously contact have mutuallydifferent pitches. For example, “a=b=c=d=e=g=h=i=j=k” and “f≠l”. Namely,in FIG. 3, the pitches of the segments 24 of Nos. 12 and 1 are differentfrom each other and from those of the other segments 24.

The operation of the present first embodiment will now be described.

In the fan motor for vehicle 10 having the above-described structure,when each of the pair of positive/negative brushes 28 contacts acrosstwo mutually adjacent segments 24 of the commutator 26, the two segments24 have the same potential and current does not flow therethrough, thusresulting in a short circuit state. In this case, the coils 23 connectedto the respective two segments 24 of the commutator result in coils inthe short circuit state. As the armature rotates, such coils in theshort circuit state serially occur, while the occurrence positions areprimarily determined depending upon the positional relation between thesegments 24 of the commutator 26 and the brushes 28.

In the fan motor for vehicle 10 according to the present firstembodiment, as described above, among the segments 24 of the commutator26, at least one of pairs of segments 24 that the pair ofpositive/negative brushes 28 simultaneously contact (e.g., the segmentshaving the pitches “f” and “l” shown in FIG. 1) have mutually differentpitches. Therefore, when each of the pair of positive/negative brushes28 contacts across the pair of segments 24 having mutually differentpitches (e.g., the segments 24 of Nos. 12 and 1 shown in FIG. 3), thecontact timing and contact-release timing of one brush 28, i.e., timingwhen the coil in the above-described short circuit state occurs andtiming when the coil is released from the short circuit state (timing ofswitching from the short circuit state to a conductive state) thereof,deviate from those of the other brush 28. (For example, as shown in FIG.3, the short circuit state-occurrence timing and the short circuitstate-release timing of the coil 23 connected to the segments 24 of Nos.12 and 1 deviate from those of the coil 23 connected to the segments 24of Nos. 6 and 7 in the short circuit state.) Accordingly, variationwidth of current waveform narrows at least in a value of electriccurrent supplied to the coil 23 (slot 22) connected to the pair ofsegments 24. As a result, vibration of the fan motor for vehicle 10,variation of rotating torque, and noise are reduced.

In the above case, one of pairs of segments 24 that the pair ofpositive/negative brushes 28 simultaneously contact have mutuallydifferent pitches. However, an increased number of pairs thereof mayhave mutually different pitches, and all of the pairs thereof may havemutually different pitches. In the cases using such structures, thevariation width even more narrows as a whole in a value of electriccurrent supplied to the respective coils (slots 22). As a result,vibration of the fan motor for vehicle 10, variation of rotating torque,and noise are even more reduced.

Next, other embodiments of the present invention will be described. Inthe following description, components basically identical to those inthe first embodiment will be referred to using the same referencenumerals as in the first embodiment, and description thereof will beomitted.

(Second Embodiment)

In a second embodiment, the plurality of segments 24 of the commutator26 comprise “reference width segments” whose peripheral width is definedby a formula of (360°/number of segments), and “variable width segments”whose peripheral width varies within a range from 1.5% to 40% withrespect to that of the “reference width segments”.

For example, in the commutator 26 shown in FIG. 5, in the case where thenumber of segments 24 is twelve, the segments having a pitch of 30° arethe “reference width segments”, and the segments having pitches of 29.5°and 30.5° are the “variable width segments”. As a whole, the segments 24include three types. In this case, the variation of the peripheral widthof the “variable width segments” with respect to that of the “referencewidth segments” is within a range of ±1.5%.

For example, in the commutator 26 shown in FIG. 6, the segments having apitch of 30° are the “reference width segments”, and the segments havingpitches of 29.4° and 30.6° are the “variable width segments”. Also inthis case, the segments 24 include three types as a whole. In this case,the variation of the peripheral width of the “variable width segments”with respect to that of the “reference width segments” is within a rangeof ±2%.

For example, in the commutator 26 shown in FIG. 7, in the case where thenumber of segments 24 is twelve, the segments having a pitch of 30° arethe “reference width segments”, and the segments having pitches of 29°and 31° are the “variable width segments”. As a whole, the segments 24include three types. In this case, the variation of the peripheral widthof the “variable width segments” with respect to that of the “referencewidth segments” is within a range of ±3.3%.

For example, in the commutator 26 shown in FIG. 8, the segments having apitch of 30° are the “reference width segments”, and the segments havingpitches of 28.5° and 31.5° are the “variable width segments”. Also inthis case, the segments 24 include three types as a whole. In this case,the variation of the peripheral width of the “variable width segments”with respect to that of the “reference width segments” is within a rangeof ±5%.

For example, in the commutator 26 shown in FIG. 9, the segments having apitch of 30° are the “reference width segments”, and the segments havingpitches of 28° and 32° are the “variable width segments”. Also in thiscase, the segments 24 include three types as a whole. In this case, thevariation of the peripheral width of the “variable width segments” withrespect to that of the “reference width segments” is within a range of±6.7%.

Further, as a modified example of the present second embodiment, theperipheral width of the plurality of segments 24 of the commutator 26 isvaried within a range from 1.5% to 40% with respect to “referenceperipheral width” defined by the formula of (360°/number of segments).

For example, in the commutator 26 shown in FIG. 10, in the case wherethe number of segments 24 is twelve, the pitch of 30° is the “referenceperipheral width”, and the peripheral width of all of the segments 24 isvaried from the “reference peripheral width” (so as to have pitches of28°, 29°, 31° and 32°). In this case, the segments 24 include four typesas a whole. In this case, the variation of the peripheral width of therespective segments 24 with respect to the “reference peripheral width”is within a range of ±6.7%.

The operation of the present second embodiment will now be described.

In the second embodiment, the plurality of segments 24 of the commutator26 comprise the “reference width segments” and the “variable widthsegments” whose peripheral width varies within a predetermined rangewith respect to that of the “reference width segments”, or comprise the“variable width segments” whose peripheral width varies within apredetermined range with respect to the predetermined “referenceperipheral width”. Therefore, a period of switching current to therespective segments 24 becomes irregular, and thus, magneticexciting-force does not concentrate on a certain frequency. Further,when each of the pair of positive/negative brushes 28 contacts acrossthe “reference width segment” and the “variable width segment”, orcontacts across two “variable width segments” having mutually differentperipheral widths, the contact timing and contact-release timing of onebrush 28, i.e., timing when the coil in the above-described shortcircuit state occurs and timing when the coil is released from the shortcircuit state (timing of switching from the short circuit state to aconductive state) thereof, deviate from those of the other brush 28.Accordingly, variation width of current waveform narrows at least in avalue of electric current supplied to the coil 23 (slot 22) connected tothe pair of segments 24. As a result, vibration of the fan motor forvehicle 10, variation of rotating torque, and noise are reduced.

FIGS. 11 and 12 show measurement data obtained by an experiment ofcharacteristics of changing magnetic exciting-force when the peripheralwidth of the respective segments 24 is varied from that of the“reference width segments” or the “reference peripheral width” asdescribed above.

In such a fan motor for vehicle 10, problematic magnetic exciting-force(magnetic noise), which results from the above-described timing when thecoil in the short circuit state occurs and the timing when the coil isreleased from the short circuit state, is noise which is not larger than5 KHz. It is clearly seen from FIGS. 11 and 12 that, in the case wherethe peripheral width of the respective segments 24 is varied from thatof the “reference width segments” or the “reference peripheral width”,the magnetic exciting-force is considerably reduced as compared with thecase where all of the segments 24 have the same pitch.

(Third Embodiment)

In a third embodiment, the plurality of segments 24 of the commutator 26comprise the “reference width segments” whose peripheral width isdefined by the formula of (360°/number of segments 24), and some typesof “variable width segments” whose peripheral width varies from that ofthe reference width segments, wherein the number of types thereof is notlarger than the number defined by a formula of (number of segments24/2)+1.

For example, in the commutator 26 shown in FIG. 13, in the case wherethe number of segments 24 is twelve, the segments having a pitch of 30°are the “reference width segments”, and the segments having pitches of28° and 32° are the “variable width segments”. As a whole, the segments24 include three types.

For example, in the commutator 26 shown in FIG. 14, the segments havinga pitch of 30° are the “reference width segments”, and the segmentshaving pitches of 28° and 32° are the “variable width segments”. Also inthis case, the segments 24 include three types as a whole.

Further, in the commutator 26 shown in FIG. 14, one of the plurality ofvariable width segments having a pitch of 32° locates opposite thevariable width segment having a pitch of 28° with respect to the centerof the commutator 26.

The variable width segments having a pitch of 32° other than the onelocating opposite the variable width segment having a pitch of 28° withrespect to the center of the commutator 26 locate respectively oppositethe variable width segments having the same pitch of 32° with respect tothe center of the commutator 26.

Furthermore, the variable width segments having a pitch of 28° otherthan the one locating opposite the variable width segment having a pitchof 32° with respect to the center of the commutator 26 locaterespectively opposite the variable width segments having the same pitchof 28° with respect to the center of the commutator 26.

One of the above-mentioned reference width segments having a pitch of30° locates opposite the other one with respect to the center of thecommutator 26.

For example, in the commutator 26 shown in FIG. 15, the segments havinga pitch of 30° are the “reference width segments”, and the segmentshaving pitches of 26°, 31° and 32° are the “variable width segments”. Inthis case, the segments 24 include four types as a whole.

For example, in the commutator 26 shown in FIG. 16, the segments havinga pitch of 30° are the “reference width segments”, and the segmentshaving pitches of 28°, 29°, 31° and 32° are the “variable widthsegments”. In this case, the segments 24 include five types as a whole.

For example, in the commutator 26 shown in FIG. 17, the segments havinga pitch of 30° are the “reference width segments”, and the segmentshaving pitches of 26°, 28°, 29°, 33° and 34° are the “variable widthsegments”. In this case, the segments 24 include six types as a whole.

For example, in the commutator 26 shown in FIG. 18, the segments havinga pitch of 30° are the “reference width segments”, and the segmentshaving pitches of 27°, 28°, 29°, 31°, 32° and 33° are the “variablewidth segments”. In this case, the segments 24 include seven types as awhole.

The operation of the present third embodiment will now be described.

In the third embodiment, the plurality of segments 24 of the commutator26 comprise the “reference width segments” and a predetermined number oftypes of “variable width segments” whose peripheral width varies fromthat of the “reference width segments”. Therefore, a period of switchingcurrent to the respective segments 24 becomes irregular, and thus,magnetic exciting-force does not concentrate on a certain frequency.Further, when each of the pair of positive/negative brushes 28 contactsacross the “reference width segment” and the “variable width segment”,or contacts across two “variable width segments” having mutuallydifferent peripheral widths, the contact timing and contact-releasetiming of one brush 28, i.e., timing when the coil in theabove-described short circuit state occurs and timing when the coil isreleased from the short circuit state (timing of switching from theshort circuit state to a conductive state) thereof, deviate from thoseof the other brush 28. Accordingly, variation width of current waveformnarrows at least in a value of electric current supplied to the coil 23(slot 22) connected to the pair of segments 24. As a result, vibrationof the fan motor for vehicle 10, variation of rotating torque, and noiseare reduced.

FIG. 19 shows measurement data obtained by an experiment ofcharacteristics of changing magnetic exciting-force when the segments 24comprise the “reference width segments” and a predetermined number oftypes of “variable width segments” whose peripheral width varies fromthat of the “reference width segments” as described above.

In such a fan motor for vehicle 10, problematic magnetic exciting-force(magnetic noise), which results from the above-described timing when thecoil in the short circuit state occurs and the timing when the coil isreleased from the short circuit state, is noise which is not larger than5 KHz. It is clearly seen from FIG. 19 that, in the case where thesegments 24 comprise the “reference width segments” and a predeterminednumber of types of “variable width segments” whose peripheral widthvaries from that of the “reference width segments”, the magneticexciting-force is considerably reduced as compared with the case whereall of the segments 24 have the same pitch.

When, for example, in the commutator 26 shown in FIG. 14, the pitches ofthe segments 24 other than the pair of variable width segments, whichare opposed to each other with respect to the center of the commutator26 and which have mutually different pitches (of 32° and 28°), arerespectively made the same as those of the segments 24 locating on theopposite sides thereof with respect to the center of the commutator 26,the segments 24 get to be easily formed.

Specifically, when the segments 24 are formed to the commutator 26,slits 32 (see FIG. 14) are formed by a cutting tool to the commutator 26to which the segments 24 have not been formed yet. In order to form theslits 32, cutting tools are connected to each other so that they arerespectively oriented toward the center of the commutator 26 in theradial direction, and a plurality of slits 32 are then formed at a timeby the cutting tools. After forming the slits 32, the cutting tools areseparated from the commutator 26, and then, the cutting tools arerotated around the center of the commutator 26, or the commutator 26itself is rotated, such that another plurality of slits 32 are formed ata time at other positions of the commutator 26 around the centerthereof.

As described above, the pitches of the segments 24 other than the pairof variable width segments, which are opposed to each other with respectto the center of the commutator 26 and which have mutually differentpitches (of 32° and 28°), are respectively the same as those of thesegments 24 locating on the opposite sides thereof with respect to thecenter of the commutator 26. Therefore, when the slits 32 are formed atother positions thereof as described above, without individuallyadjusting the respective rotating angles of the plurality of cuttingtools, all of the cutting tools or the commutator 26 is integrallyrotated around the center of the commutator 26 by an angle correspondingto the pitches of the other segments 24 so as to form the slits 32 tothe commutator 26. As a result, the operation efficiency is improved.

(Fourth Embodiment)

In the same manner as the commutator 26 shown in FIG. 13 in theabove-described second embodiment, in the commutator 26 shown in FIG. 21in the present embodiment, the number of segments 24 is twelve, thesegments having a pitch of 30° are the “reference width segments”, andthe segments having pitches of 28° and 32° are the “variable widthsegments”. As a whole, the segments 24 include three types.

As shown in FIGS. 20 and 21, in the present embodiment, a plurality ofpawls 30 are formed to the commutator 26 so that they respectivelycorrespond to the segments 24. (Although the pawls 30 are respectivelyformed to the segments 24 of the commutator 26 also in each of theabove-described embodiments, the pawls 30 have not especially beendescribed so far.)

The pawls 30 respectively extend from the segments 24 of the commutator26, and portions of the windings forming the coils 23 are respectivelyengaged with the pawls 30 in the conductive state. Accordingly, thecoils 23 are respectively conductive to the segments 24 of thecommutator 26.

The pawls for a conventional commutator have been respectively formedbasically at the peripheral centers of the segments. In the presentembodiment, although the pawls 30 respectively extend from thevicinities of the peripheral centers of the segments 24, the pawls 30respectively extend from the segments 24 at predetermined angularintervals around the center of the commutator 26 (the interval is 30°when there are twelve segments 24 as in the present embodiment).

As described above, in the commutator 26 shown in FIG. 20 (FIG. 13), thepitches of the variable width segments 24 are 32° and 28°. In thepresent embodiment, however, the pawls 30 are formed at intervals of30°. Thus, in the variable width segment 24 having a pitch of 32°, thepawl 30 is formed at a position clockwise shifted by 1° from theperipheral center thereof. Therefore, although the segment 24, which iscounterclockwise adjacent to the variable width segment 24 having apitch of 32°, has a pitch of 30°, the pawl 30 is formed at a positionclockwise shifted by 1° from the peripheral center thereof. Further, inthe variable width segment 24 having a pitch of 28°, the pawl 30 isformed at a position clockwise shifted by 1° from the peripheral centerthereof.

However, in the segment 24 having a pitch of 30°, which iscounterclockwise adjacent to the variable width segment 24 having apitch of 28°, the pawl 30 is formed at the peripheral center thereof dueto the pitch between the pawls 30.

As described above, since the structure of the commutator 26 in thepresent embodiment is the same as that shown in FIG. 13 in the secondembodiment, basically the same operation is achieved and the sameeffects are obtained as in the second embodiment.

Further, in the present embodiment, the pawls 30, with which portions ofthe windings forming the coils 23 are respectively engaged, are formedat regular intervals basically regardless of the pitches of therespective segments 24 of the commutator 26. Accordingly, when thewindings are serially engaged with the respective pawls 30, if thecommutator 26 is rotated by a predetermined angle around the axisthereof, the winding engages with the next pawl 30. As a result, thewinding device such as a robot is easily controlled.

INDUSTRIAL APPLICABILITY

As described above, the electric rotating machine and the fan motor forvehicle according to the present invention are utilized for any types ofelectric rotating machines and fan motors for vehicle in which basicallybrushes slide on a commutator, such as a motor for ventilating of anair-conditioner to be provided in a vehicle.

1. An electric rotating machine comprising: a motor yoke; a field magnetfixed inside the motor yoke; an armature comprising a rotating shaft ata central portion of a laminated core on which windings are wound,wherein a commutator comprising a plurality of segments, in which atleast one pair of segments comprise mutually different peripheralwidths, is attached to an end portion of the rotating shaft; and aplurality of brushes disposed opposite each other with the commutatortherebetween, so as to slide on the commutator of the armature.
 2. Theelectric rotating machine of claim 1, wherein the plurality of segmentsinclude variable width segments, and the variable width segments eachcomprise a peripheral width varied within a range from 1.5% to 40% withrespect to a reference width defined by a first formula of (360°/numberof segments).
 3. The electric rotating machine of claim 2, wherein theplurality of segments include some types of variable width segmentswhose peripheral width varies from the reference width, wherein thenumber of types thereof is not larger than the number defined by asecond formula of (number of segments/2)+1.
 4. The electric rotatingmachine of claim 3, wherein the plurality of segments include referencewidth segments, and the reference width segments each comprise aperipheral width substantially equal to the reference width.
 5. Theelectric rotating machine of claim 4, wherein at least one of thevariable width segments comprises a peripheral width widened at apredetermined rate with respect to the reference width, and at leastanother variable width segment comprises a peripheral width narrowed ata rate substantially equal to the predetermined rate with respect to thereference width.
 6. The electric rotating machine of claim 5, wherein aperipheral width of one of the variable width segments is different froma peripheral width of another variable width segment provided oppositesaid one of the variable width segments with respect to a center of thecommutator, and peripheral widths of segments other than said one andsaid another variable width segments are respectively substantiallyequal to peripheral widths of the segments respectively providedopposite said segments other than said one and said another variablewidth segments with respect to the center of the commutator.
 7. Theelectric rotating machine of claim 6, further comprising a plurality ofpawls, which are respectively formed to the plurality of segments andwith which portions of the windings are respectively engaged in aconductive state, wherein at least one of the plurality of pawls isprovided at a position displaced from the peripheral center of therespective segment.
 8. The electric rotating machine of claim 2, whereinthe plurality of segments include reference width segments, and thereference width segments each comprise a peripheral width substantiallyequal to the reference width.
 9. The electric rotating machine of claim8, wherein at least one of the variable width segments comprises aperipheral width widened at a predetermined rate with respect to thereference width, and at least another variable width segment comprises aperipheral width narrowed at a rate substantially equal to thepredetermined rate with respect to the reference width.
 10. The electricrotating machine of claim 2, wherein at least one of the variable widthsegments comprises a peripheral width widened at a predetermined ratewith respect to the reference width, and at least another variable widthsegment comprises a peripheral width narrowed at a rate substantiallyequal to the predetermined rate with respect to the reference width. 11.The electric rotating machine of claim 2, further comprising a pluralityof pawls, which are respectively formed to the plurality of segments andwith which portions of the windings are respectively engaged in aconductive state, wherein at least one of the plurality of pawls isprovided at a position displaced from the peripheral center of therespective segment.
 12. The electric rotating machine of claim 1,wherein the plurality of segments include some types of variable widthsegments whose peripheral width varies from a reference width, whereinthe number of types thereof is not larger than the number defined by asecond formula of (number of segments/2)+1.
 13. The electric rotatingmachine of claim 12, wherein the plurality of segments include referencewidth segments, and the reference width segments each comprise aperipheral width substantially equal to the reference width.
 14. Theelectric rotating machine of claim 12, further comprising a plurality ofpawls, which are respectively formed to the plurality of segments andwith which portions of the windings are respectively engaged in aconductive state, wherein at least one of the plurality of pawls isprovided at a position displaced from the peripheral center of therespective segment.
 15. The electric rotating machine of claim 1,further comprising a plurality of pawls, which are respectively formedto the plurality of segments and with which portions of the windings arerespectively engaged in a conductive state, wherein at least one of theplurality of pawls is provided at a position displaced from theperipheral center of the respective segment.
 16. A fan motor for vehiclecomprising: a motor yoke; a field magnet fixed inside the motor yoke; anarmature comprising a rotating shaft at a central portion of a laminatedcore on which windings are wound, wherein a commutator comprising aplurality of segments, in which at least one pair of segments comprisemutually different peripheral widths, is attached to an end portion ofthe rotating shaft; a plurality of brushes disposed opposite each otherwith the commutator therebetween, so as to slide on the commutator ofthe armature; and a fan attached to the rotating shaft so as to rotateas the armature rotates.
 17. The fan motor for vehicle of claim 16,wherein the plurality of segments include variable width segments, andthe variable width segments each comprise a peripheral width variedwithin a range from 1.5% to 40% with respect to a reference widthdefined by a first formula of (360°/number of segments).
 18. The fanmotor for vehicle of claim 17, wherein the plurality of segments includesome types of variable width segments whose peripheral width varies fromthe reference width, wherein the number of types thereof is not largerthan the number defined by a second formula of (number of segments/2)+1;wherein at least one of the variable width segments comprises aperipheral width widened at a predetermined rate with respect to thereference width, and at least another variable width segment comprises aperipheral width narrowed at a rate substantially equal to thepredetermined rate with respect to the reference width; and wherein aperipheral width of one of the variable width segments is different froma peripheral width of another variable width segment provided oppositesaid one of the variable width segments with respect to a center of thecommutator, and peripheral widths of segments other than said one andsaid another variable width segments are respectively substantiallyequal to peripheral widths of the segments respectively providedopposite said segments other than said one and said another variablewidth segments with respect to the center of the commutator.
 19. The fanmotor for vehicle of claim 17, wherein at least one of the variablewidth segments comprises a peripheral width widened at a predeterminedrate with respect to the reference width, and at least another variablewidth segment comprises a peripheral width narrowed at a ratesubstantially equal to the predetermined rate with respect to thereference width.
 20. The fan motor for vehicle of claim 16, wherein theplurality of segments include some types of variable width segmentswhose peripheral width varies from a reference width, wherein the numberof types thereof is not larger than the number defined by a secondformula of (number of segments/2)+1.